1. Field of the Invention
The present invention relates to a color image display device and a projection-type image display apparatus that display a color image with one light valve as a light modulating member.
2. Description of Related Art
Along with a sufficient supply of video equipment and video software such as a video tape recorder and a video disk player, the demand for a large screen image display apparatus for enjoying powerful images has become intensified in recent years. As a conventional large screen image display apparatus, there is an image display apparatus that uses a liquid crystal panel (a light valve) for an image display portion so as to modulate light emitted from a light source spatially by the liquid crystal panel and project an image onto a screen. Currently commercialized image display apparatus using the liquid crystal panel can be classified roughly into a three-plate system using three liquid crystal panels and a single-plate system using one liquid crystal panel.
FIG. 21 shows a configuration of one example of the conventional three-plate system image display apparatus.
Light emitted from a lamp 901 as a light source and light reflected by a reflection mirror 902 are converged by a focusing lens 903, and then separated into red, green and blue components of primary colors by a blue-reflecting dichroic mirror 904 and a green-reflecting dichroic mirror 905. Light beams of these primary colors respectively are directed to a liquid crystal panel for red light 912, a liquid crystal panel for green light 913 and a liquid crystal panel for blue light 914, combined by a color combination prism 915, and then projected onto a screen 917 by a projection lens 916. In this figure, total reflection mirrors 906, 907 and 908 change optical paths of the light beams, and lenses 909, 910 and 911 adjust the incident angles of the light beams entering the respective liquid crystal panels. A white light source used for the lamp 901 as the light source is, for example, a discharge-type extra-high pressure mercury vapor lamp or metal halide lamp, or a thermoluminescence-type halogen lamp.
The liquid crystal panel for red light 912, the liquid crystal panel for green light 913 and the liquid crystal panel for blue light 914 are driven by a video signal for red light, a video signal for green light and a video signal for blue light respectively. The light irradiated by the lamp 901 is modulated spatially when passing through the respective liquid crystal panels, and projected onto the screen 917 by the projection lens 916 as an image.
FIG. 22 shows a configuration of one example of the conventional single-plate system image display apparatus.
Light emitted from a lamp 931 as a light source and light reflected by a reflection mirror 932 are converged by a focusing lens 933, and then irradiated on a liquid crystal panel 940. The liquid crystal panel 940 is constituted by a mosaic color filter substrate 941 and a TFT array substrate 942 as shown in FIG. 23. When a white light beam from the lamp 931 passes through the color filter 941, red, green and blue light beams of primary colors are obtained. These light beams of primary colors that have passed through the liquid crystal panel 940 are projected onto a screen 935 by a projection lens 934.
In the conventional three-plate system image display apparatus described above (see FIG. 21), the liquid crystal panel is driven by the video signal so that the liquid crystal panel changes transmittance of the light, thereby modulating the light spatially so as to display the image. Since the entire spectrum of the white light from the lamp can be utilized, the image display apparatus of this system has a high efficiency of light utilization. However, the necessity of the three liquid crystal panels, a color separation optical system, a color combination optical system and a convergence adjusting mechanism between the liquid crystal panels has posed a problem in that this system is relatively expensive.
On the other hand, the conventional single-plate system image display apparatus described above (see FIGS. 22 and 23) is compact and inexpensive because the image formed on the liquid crystal panel having the mosaic color filter simply is magnified and projected onto the screen. However, since this system obtains desired light of the primary colors by absorbing light with an unwanted color using the color filter, the efficiency of light utilization is low (one-third or less), making it very difficult to increase brightness.
In an image display apparatus using a single image display panel, it is a first object of the present invention to provide a color image display device and a projection-type image display apparatus that can utilize light from a light source effectively and display a high-brightness image. Also, it is a second object of the present invention to provide a small color image display device and a small projection-type image display apparatus using a single image display panel. Furthermore, in the apparatus achieving the above objects, it is a third object of the present invention to provide a color image display device and a projection-type image display apparatus that are provided with a preferable adjusting means.
In order to achieve the above-mentioned objects, the present invention has the following configurations.
A color image display device according to a first configuration of the present invention includes a light source portion for emitting respective light beams of red, green and blue, an image display panel provided with many pixels for modulating an incident light according to color signals of at least red, green and blue, an optical system for directing the respective light beams to enter the image display panel so that the respective light beams from the light source portion form belt-like illuminated regions at different positions on the image display panel and the regions illuminated by the respective light beams move continuously on the image display panel, and an image display panel driving circuit for driving each of the pixels of the image display panel. Each of the pixels is driven by a signal corresponding to a color of light entering this pixel, thereby displaying a color image. The respective light beams are directed to enter the image display panel so that the illuminated regions adjacent to each other on the image display panel partially overlap each other. The pixel that the light beams of the overlapping two colors enter is driven by a brightness signal component.
With this first configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, since the red, green and blue light beams are irradiated simultaneously on different regions on the image display panel so as to display red, green and blue images on these regions simultaneously, it is possible to utilize light effectively and display a high-brightness image.
Also, unlike the case of the conventional color image display apparatus using the single image display panel (see FIG. 22), the image display panel does not have the pixels exclusively for displaying the red, green and blue images. Therefore, ⅓ of the number of the pixels of the conventional image display panel (see FIG. 23) is sufficient for the image display panel of the present invention, allowing a cost reduction.
Furthermore, by partially overlapping the illuminated regions of the adjacent two colors on the image display panel, a focused area of the light beams can be made larger than that in the case without any overlapping portion, achieving a smaller focusing optical system, and making it possible to reduce the size of the entire device. Moreover, a point light source does not have to be used. In addition, by using the light of the overlapping portions for the display of a brightness component, the light from the light source portion can be utilized effectively, achieving a still higher brightness.
In the first configuration described above, it is preferable to further include a video signal processing circuit in which the color signals of red, green and blue are inputted, the brightness signal component is detected from the color signals, and signals obtained by subtracting the brightness signal component from the color signals and the brightness signal component are outputted to the image display panel driving circuit. With this preferable configuration, it is possible to display a bright color image with excellent color purity and brightness gradation characteristics.
Next, a color image display device according to a second configuration of the present invention includes a light source portion for emitting respective light beams of red, green and blue, an image display panel provided with many pixels for modulating an incident light according to color signals of at least red, green and blue, an optical system for directing the respective light beams to enter the image display panel so that the respective light beams from the light source portion form belt-like illuminated regions at different positions on the image display panel and the regions illuminated by the respective light beams move continuously on the image display panel, and an image display panel driving circuit for driving each of the pixels of the image display panel. Each of the pixels is driven by a signal corresponding to a color of light entering this pixel, thereby displaying a color image. The color image display device further includes a drive timing adjusting circuit for adjusting a timing of the signal that drives each of the pixels so as to correspond to a change of the color of light entering this pixel.
With this second configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, since the red, green and blue light beams are irradiated simultaneously on different regions on the image display panel so as to display red, green and blue images on these regions simultaneously, it is possible to utilize light effectively and display a high-brightness image.
Also, unlike the case of the conventional color image display apparatus using the single image display panel (see FIG. 22), the image display panel does not have the pixels exclusively for displaying the red, green and blue images. Therefore, ⅓ of the number of the pixels of the conventional image display panel (see FIG. 23) is sufficient for the image display panel of the present invention, allowing a cost reduction.
Furthermore, by adjusting the timing of the driving signal to be inputted to each of the pixels using the drive timing adjusting circuit, a switch timing of the color of light entering each of the pixels and a timing of the driving signal to be inputted to this pixel can be matched. As a result, the relative displacement of the regions illuminated by the respective light beams and width variation thereof in a moving direction owing to a structural tolerance of the optical systems can be corrected, thus displaying a color image with an excellent white balance.
In the second configuration described above, it is preferable that the drive timing adjusting circuit includes a test pattern switching controlling circuit provided with a circuit for outputting a test pattern signal and a switch circuit for selecting either the test pattern signal or an inputted video signal, and a delay controlling circuit for delaying an output signal of the test pattern switching controlling circuit for an arbitrary time. With this preferable configuration, it is possible to adjust the white balance easily.
Next, a color image display device according to a third configuration of the present invention includes a light source portion for emitting respective light beams of red, green and blue, an image display panel provided with many pixels for modulating an incident light according to color signals of at least red, green and blue, an optical system for directing the respective light beams to enter the image display panel so that the respective light beams from the light source portion form belt-like illuminated regions at different positions on the image display panel and the regions illuminated by the respective light beams move continuously on the image display panel, and an image display panel driving circuit for driving each of the pixels of the image display panel. Each of the pixels is driven by a signal corresponding to a color of light entering this pixel, thereby displaying a color image. The optical system includes a first optical system that the respective light beams from the light source portion enter, a rotating polygon mirror that has a plurality of reflecting surfaces and makes the respective light beams perform a scanning when the respective light beams having left the first optical system enter the reflecting surface and are reflected, and a second optical system for directing the respective light beams from the rotating polygon mirror to the image display panel. Chief rays of the respective light beams having left the first optical system enter the reflecting surface of the rotating polygon mirror at different positions from each other in a rotation direction of the rotating polygon mirror at different incident angles from each other, whereby the chief rays of the respective light beams reflected by the reflecting surface enter the second optical system at different angles from each other, and then enter the image display panel at different positions. The first optical system has an adjusting mechanism for adjusting the incident angles at which the chief rays of the respective light beams having left the first optical system enter the reflecting surface of the rotating polygon mirror, for each of the light beams.
With this third configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, since the red, green and blue light beams are irradiated simultaneously on different regions on the image display panel so as to display red, green and blue images on these regions simultaneously, it is possible to utilize light effectively and display a high-brightness image.
Also, unlike the case of the conventional color image display apparatus using the single image display panel (see FIG. 22), the image display panel does not have the pixels exclusively for displaying the red, green and blue images. Therefore, ⅓ of the number of the pixels of the conventional image display panel (see FIG. 23) is sufficient for the image display panel of the present invention, allowing a cost reduction.
Furthermore, by adjusting the relative positions of the illuminated regions of the respective light beams using the adjusting mechanism, a switch timing of the color of light entering each of the pixels and a timing of the driving signal to be inputted to this pixel can be matched. As a result, the relative displacement of the regions illuminated by the respective light beams owing to a structural tolerance of the optical systems can be corrected, thus displaying a color image with an excellent white balance.
In addition, the optical system is constituted by the rotating polygon mirror and the peripheral focusing optical system, making it possible to reduce the size, weight and cost of the device.
In the second and third configurations described above, it is preferable that the respective light beams are directed to enter the image display panel so that the illuminated regions adjacent to each other on the image display panel partially overlap each other, and the pixel that the light beams of the overlapping two colors enter is driven by a brightness signal component. With this preferable configuration, by partially overlapping the illuminated regions of the adjacent two colors on the image display panel, a focused area of the light beams can be made larger than that in the case without any overlapping portion, achieving a smaller focusing optical system, and making it possible to reduce the size of the entire device. Moreover, a point light source does not have to be used. In addition, by using the light of the overlapping portions for the display of a brightness component, the light from the light source portion can be utilized effectively, achieving a still higher brightness.
In the above preferable configurations, it is preferable further to include a video signal processing circuit in which the color signals of red, green and blue are inputted, the brightness signal component is detected from the color signal, and signals obtained by subtracting the brightness signal component from the color signals and the brightness signal component are outputted to the image display panel driving circuit. With this preferable configuration, it is possible to display a bright color image with excellent color purity and brightness gradation characteristics.
Alternatively, in the second and third configurations described above, a black display belt may be formed in a border of the illuminated regions adjacent to each other on the image display panel, and the pixel outside the black display belt may be driven by the signal corresponding to the color of light entering this pixel. With this configuration, it is possible to prevent the light beams of different colors from entering one pixel at the same time so as to deteriorate the color purity of the displayed image, thereby providing a color display having an excellent color reproducibility.
Next, a color image display device according to a fourth configuration of the present invention includes a light source portion for emitting respective light beams of red, green and blue, an image display panel provided with many pixels for modulating an incident light according to color signals of at least red, green and blue, an optical system for directing the respective light beams to enter the image display panel so that the respective light beams from the light source portion form belt-like illuminated regions at different positions on the image display panel and the regions illuminated by the respective light beams move continuously on the image display panel, and an image display panel driving circuit for driving each of the pixels of the image display panel. A black display belt is formed in a border of the illuminated regions adjacent to each other on the image display panel, and the pixel outside the black display belt is driven by a signal corresponding to a color of light entering this pixel.
With this fourth configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, since the red, green and blue light beams are irradiated simultaneously on different regions on the image display panel so as to display red, green and blue images on these regions simultaneously, it is possible to utilize light effectively and display a high-brightness image.
Also, unlike the case of the conventional color image display apparatus using the single image display panel (see FIG. 22), the image display panel does not have the pixels exclusively for displaying the red, green and blue images. Therefore, ⅓ of the number of the pixels of the conventional image display panel (see FIG. 23) is sufficient for the image display panel of the present invention, allowing a cost reduction.
Furthermore, a black display belt is formed in a border of the illuminated regions adjacent to each other on the image display panel, making it possible to prevent the light beams of different colors from entering one pixel at the same time so as to deteriorate the color purity of the displayed image, thereby providing a color display having an excellent color reproducibility.
In the first, second and fourth configurations described above, it is preferable that the optical system includes a first optical system that the respective light beams from the light source portion enter, a rotating polygon mirror that has a plurality of reflecting surfaces and makes the respective light beams perform a scanning when the respective light beams having left the first optical system enter the reflecting surface and are reflected, and a second optical system for directing the respective light beams from the rotating polygon mirror to the image display panel, and chief rays of the respective light beams having left the first optical system enter the reflecting surface of the rotating polygon mirror at different positions from each other in a rotation direction of the rotating polygon mirror at different incident angles from each other, whereby the chief rays of the respective light beams reflected by the reflecting surface enter the second optical system at different angles from each other, and then enter the image display panel at different positions. With this preferable configuration, the optical system is constituted by the rotating polygon mirror and the peripheral focusing optical system, making it possible to reduce the size, weight and cost of the device.
Also, in the first, second and fourth configurations described above, the optical system may include a first optical system that the respective light beams from the light source portion enter, an optical path turning device for switching optical paths of the respective light beams having left the first optical system in synchronization with a video signal, and a second optical system for directing the respective light beams having left the optical path turning device to the image display panel.
In this case, the optical path turning device can be constituted so as to switch the optical paths of the respective light beams by rotating a structure using an optical fiber, a polygon mirror or a prism.
Also, in the first to fourth configurations described above, the image display panel can be a transmission-type light valve or a reflection-type light valve.
Next, a projection-type image display apparatus of the present invention includes the color image display device with any of the first to fourth configurations described above as an image display portion and a projection optical system for magnifying and projecting an image of the image display panel.
With this configuration, the color image can be displayed using only one image display panel having neither a color filter nor a pixel exclusively for the respective light beams. Moreover, it is possible to utilize light effectively and display a high-brightness image.
In addition, ⅓ of the number of the pixels of the conventional projection-type image display apparatus that displays a color image using the single image display panel is sufficient for the image display panel of the present invention, allowing a cost reduction.